Pressure compensation behavior inside an EWOD oscillator

We present a method to study the pressure compensation behavior of polar fluids immersed in non-polar insulating fluids, which are actuated using the "electrowetting on dielectric (EWOD)" effect inside a closed tube with a pressure compensation channel. The electrowetting effect yields to a pressure difference inside the tube, the so called Laplace pressure. The pressure field for various viscosities of the surrounding fluid is modeled using finite element analysis (FEA) for the Navier-Stokes equation. The time dependent pressure response and the viscous damping of the fluid oscillations help to establish a relation to the fluid´s dynamic viscosity. In a second step we compare the pressure response for a given pressure compensation channel diameter after actuating the polar fluid. When the polar droplet reaches the edge of the electrode, the driving force vanishes and the pressures before and behind the polar droplet begin to settle to its initial value. The generated pressure difference can be linked to the surrounding non-polar fluid´s viscosity and density. Finally, we introduce the design and fabrication of an EWOD device capable of performing the actuation schemes considered in the simulations.